• 대한수학회지
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• 제57권3호
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• pp.707-719
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• 2020

In this article we study almost contact manifolds admitting weakly Einstein metrics. We first prove that if a (2n + 1)-dimensional Sasakian manifold admits a weakly Einstein metric, then its scalar curvature s satisfies -6 ⩽ s ⩽ 6 for n = 1 and -2n(2n + 1) ${\frac{4n^2-4n+3}{4n^2-4n-1}}$ ⩽ s ⩽ 2n(2n + 1) for n ⩾ 2. Secondly, for a (2n + 1)-dimensional weakly Einstein contact metric (κ, μ)-manifold with κ < 1, we prove that it is flat or is locally isomorphic to the Lie group SU(2), SL(2), or E(1, 1) for n = 1 and that for n ⩾ 2 there are no weakly Einstein metrics on contact metric (κ, μ)-manifolds with 0 < κ < 1. For κ < 0, we get a classification of weakly Einstein contact metric (κ, μ)-manifolds. Finally, it is proved that a weakly Einstein almost cosymplectic (κ, μ)-manifold with κ < 0 is locally isomorphic to a solvable non-nilpotent Lie group.

• 생약학회지
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• 제40권1호
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• pp.13-17
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• 2009

It was previously reported that yeast elicitor transiently increased oleanolic acid and ursolic acid in Scutellaria baicalensis suspension cultures and also doubled phospholipase $A_2$ ($PLA_2$) activity. Thus, $PLA_2$ was purified from the soluble fractions of S. baicalensis suspension cultures and the characters of the purified $PLA_2$ were identified. The $PLA_2$ was purified about 160 times compared with the starting soluble-protein extract from S. baicalensis suspension culture cells. The purified protein showed a molecular mass of about 43 kDa by SDS-PAGE. The purified plant $PLA_2$ had a neutral pH optimum (pH 7.0) and required $Ca^{2+}$ for activity. The $PLA_2$ activity was inhibited by mammalian $PLA_2$ inhibitors such as 5,8,11,14-eicosatetraynoic acid(ETYA) and arachidonyl trifluoromethyl ketone ($AACOCF_3$).

• Bulletin of the Korean Chemical Society
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• 제26권6호
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• pp.930-934
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• 2005

A chloroform membrane system containing a given mixture of benzylaza-12-crown-4 and oleic acid is introduced for the selective and efficient transport of $Pb^{2+}$ ion. The transport was capable of moving metal ions ‘up-hill’. In the presence of ${S_2O_3}^{2-}$ion as a suitable metal ion acceptor in the receiving phase, the amount of lead ion transport across the liquid membrane after 150 minutes is (95.0 ${\pm}$ 1.7)%. The selectivity and efficiency of lead transport from aqueous solution containing $Tl^+,\;Ag^+,\;Mg^{2+},\;Ca^{2+},\;Co^{2+},$ $Ni^{2+},\;Cu^{2+},\;Zn^{2+},\;Hg^{2+}$ and $Cd^{2+}$were investigated. In the presence of thiosulfate as a suitable masking agent in the source phase, the interfering effects of $Ag^+\;and\;Cu^{2+}$ were diminished drastically.

• Bulletin of the Korean Chemical Society
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• 제16권5호
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• pp.449-453
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• 1995

An exact quantum mechanical theory is employed to treat predissociation process of the $A^2{\Sigma}^+$ state of OH. The widths and positions of the lower (v= 2 and v= 3) rovibrational levels are calculated. Energy shifts of the resonances from the zeroth order (pure Hund'scase (b)) positions are shown to be small for N $\leq$ 10, indicating that the $A^2{\Sigma}^+$ state can be described as case (b) very well for low N. Due to the differential interactions of the $A^2{\Sigma}^+_{1/2}$ and $A^2{\Sigma}^+_{-1/2}$ states with $X^2II$and $2^2II$ states, small splittings between the $F_1$ and $F_2$ levels are predicted. Calculated lifetimes of the resonances agree with experimental results reasonably well.

• Bulletin of the Korean Chemical Society
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• 제19권2호
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• pp.155-159
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• 1998

o-(2-Vinyloxyethoxy)benzylidenemalononitrile (4a), methyl o-(2-vinyloxyethoxy)benzylidenecyanoacetate (4b), m-(2-vinyloxyethoxy)benzylidenemalononitrile (5a), methyl m-(2-vinyloxyethoxy)benzylidenecyanoacetate (5b), p-(2-vinyloxyethoxy)benzylidenemalononitrile (6a), and methyl p-(2-vinyloxyethoxy)benzylidenecyanoacetate (6b) were prepared by the condensation of o-(2-vinyloxyethoxy)benzaldehyde (1), m-(2-vinyloxyethoxy)benzaldehyde (2), and p-(2-vinyloxyethoxy)benzaldehyde (3) with malononitrile or methyl cyanoacetate, respectively. Bifunctional vinyl ether monomers 4a-b and 6a-b polymerized readily with cationic initiators to give polymers with the NLO-chromophores o- and p-oxybenzylidenemalononitrile or o- and p-oxybenzylidenecyanoacetate in side chain at -60 ℃, while meta-isomers 5a and 5b gave lower yields of polymers under the same conditions. The resulting polymers 7-9 were soluble in common organic solvents and the inherent viscosities of polymers were in the range of 0.20-0.30 dL/g in acetone. Solution-cast films were clear and brittle, showing Tg values in the range of 40-70 ℃.

• Korean Journal of Mathematics
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• 제26권1호
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• pp.75-85
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• 2018

In this paper, we study nonconstant warping functions on an Einstein warped product manifold $M=B{\times}_{f^2}F$ with a warped product metric $g=g_B+f(t)^2g_F$. And we consider a 2-dimensional base manifold B with a metric $g_B=dt^2+(f^{\prime}(t))^2du^2$. As a result, we prove the following: if M is an Einstein warped product manifold with a 2-dimensional base, then there exist generally nonconstant warping functions f(t).

• 한국독성학회:학술대회논문집
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• 한국독성학회 2002년도 Molecular and Cellular Response to Toxic Substances
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• pp.68-88
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• 2002

Phospholipase A$_2$ (s) are esterases that hydrolyze the sn-2 ester bond in phospholipids, releasing a fatty acid and a lysophospholipid. We previously showed that most PLA$_2$ activity in rabbit renal proximal tubule cells (RPTC) was Ca$\^$2+/-independent, localized to the endoplasmic reticulum (ER-iPLA$_2$), and inhibited by the specific Ca$\^$2+/-independent PLA$_2$ inhibitor bromoenol lactone (BEL).(omitted)

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2001년도 추계학술발표대회
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• pp.325-328
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• 2001

Teicoplanin is a glycopeptide antibiotic produced by Actinoplanes teichomyceticus novo sp. A TCC 31121. It is active against Gram-positive bacteria and it is under evaluation for use in man. Teicoplanin mixture in fermentation broth contains major amounts of teicoplanin $A_1$ and $A_2$ and a minor amount tcicoplanin of $A_3$. Commercial teicoplanin product is composed of five major components of very similar polarity, designated T-$A_2$-l, 2, 3, 4 and 5, and the more polor component, designated T -$A_3$. The culture conditions were studied in order that hydrophilic teicoplanin $A_2$ components are more produced but hydrophobic teicoplanin $A_1$ with lower bioactivity are less produced in submerged culture. Effects of culture pH and nutrients on the biosynthes ratio of teicoplanin $A_1$ and $A_2$ were confirmed in flask culture using MOPS buffer system through TLC, bioautography and bioassay. It was elucidated that optimal pH is 7.4 for teicoplanin $A_2$ biosynthesis but is 5.2 for teicoplanin $A_1$ biosynthesis, and that trace elements stimulate $A_2$ production but malt extract stimulate $A_1$production.

• 한국어류학회지
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• 제28권2호
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• pp.125-133
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• 2016

전 세계 상어류 (상어구 Selachii)는 약 510종이 유효하고, 우리나라에서는 8목 19과 30속 43종이 보고되었다. 우리나라에 분포하는 상어류 43종 모두가 세계자연보존연맹 적색목록 (IUCN Red List)에 등재되었으며, IUCN 등급별 종 수 및 비율은 위기 (EN) 상태 1종 (2.3%) (vs. 전 세계 15종, 3.2%), 취약 (VU) 11종 (25.6%) (vs. 48종, 10.3%), 준위협 (NT) 10종 (23.3%) (vs. 67종, 14.4%), 관심대상 (LC) 9종 (20.9%) (vs. 115종, 24.7%), 정보부족 (DD) 12종 (27.9%) (vs. 209종, 44.9%)이었으며, 위급 (CR)에 해당하는 종은 전 세계에는 11종 (2.4%)인데 우리나라에 서식하는 종은 없었다. 한반도 해역에 분포하는 상어류 중 멸종우려 (Threatened)에 해당하는 12종과 적색목록 범주와 평가는 다음과 같다: 홍살귀상어 (EN, A2bd+4bd), 고래상어 (VU, A2bd+3d), 돌묵상어 (VU, A2ad+3d), 백상아리 (VU, A2cd+3cd), 청상아리 (VU, A2abd+3bd+4abd), 환도상어 (VU, A2d+4d), 횐배환도상어 (VU, A2bd+3bd+4bd), 흉상어 (VU, A2bd+4bd), 귀상어 (VU, A2bd+3bd+4bd), 곱상어 (VU, A2bd+3bd+4bd), 전자리상어 (VU, A2d+4d), 범수구리 (VU, A2d+4d). 멸종 위기 야생동 식물종 국제교역협약 (CITES) 부속서에 전 세계의 연골어류 중 18종이 등재되었으며, 우리나라 해역에 분포하는 상어류는 고래상어, 돌묵상어, 백상아리, 홍살귀상어, 귀상어 등 5종이 부속서 II에 포함되었다. 북태평양에 분포하는 곱상어의 학명 Squalus acanthias는 S. suckleyi로, 북서태평양의 모조리상어는 S. megalops에서 S. brevirostris로 변경되었다.

• 대한화학회지
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• 제38권5호
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• pp.372-376
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• 1994

Penicillin으로부터 유도된 4-mercaptoazetidin-2-one(2a)은 염기조건에서 불안정하지만 Et3N이나 pyridine 염기하에서 acetyl chloride, methyl chloroformate, ethyl iodoacetate, diethyl azodicarboxylate 등의 친전자체와 반응하여 sulfur에 acetyl, methoxycarbonyl, ethoxycarbonylmethyl, diethoxycarbonylhydrazineo원자단이 부착된 화합물이 된다. 반면 thiol의 methylation은 methyl iodide와의 반응으로 얻을 수 없고 diazomethane을 사용해야 한다. 또한 화합물 2a의 이성질체인 화합물 3a의 반응성도 화합물 2a와 거의 비슷하다.